Figure 3

Ptpn11 deletion in Ctsk-expressing cells causes expansion of novel chondroprogenitor cell population within the Perichondrial Groove of Ranvier. a, Flow cytometric analysis showing YFP⁺ cells from pooled epiphyseal cartilage from 5–7 Ctsk-Control/YFP mice; note increased percentage of such cells in 2-week-old Ctsk-KO/YFP mice. CC: Chondroid cells. b, Flow cytometric analysis of YFP⁺ perichondrial cells showing staining for CD31, CD44, CD90, and CD166. Data in panels a and b are from a single experiment; similar results were obtained in 2 additional experiments. c, Immunofluorescence micrograph showing Stro1 and Jagged1 expression in YFP⁺ perichondrial cells. Nuclei are stained with DAPI. Note enhanced intensity of Stro1 and Jagged staining in Ctsk-KO cells. Data shown are from single mice of each genotype; two additional mice were analyzed for each genotype with similar results. d, CCPs give rise to cartilage, fat and bone. FACS-purified YFP⁺ cells from 5–7 mice were subjected to differentiation assays in triplicate. After 2–3 weeks of culture (see Methods), cells were fixed and stained with Alcian blue, Oil red, and Alizarin red to visualize the formation of cartilage, fat, and bone tissue, respectively.